• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.477-477
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• 2008

For more than three decades, the gate dielectrics in CMOS devices are $SiO_2$ because of its blocking properties of current in insulated gate FET channels. As the dimensions of feature size have been scaled down (width and the thickness is reduced down to 50 urn and 2 urn or less), gate leakage current is increased and reliability of $SiO_2$ is reduced. Many metal oxides such as $TiO_2$, $Ta_2O_4$, $SrTiO_3$, $Al_2O_3$, $HfO_2$ and $ZrO_2$ have been challenged for memory devices. These materials posses relatively high dielectric constant, but $HfO_2$ and $Al_2O_3$ did not provide sufficient advantages over $SiO_2$ or $Si_3N_4$ because of reaction with Si substrate. Recently, $HfO_2$ have been attracted attention because Hf forms the most stable oxide with the highest heat of formation. In addition, Hf can reduce the native oxide layer by creating $HfO_2$. However, new gate oxide candidates must satisfy a standard CMOS process. In order to fabricate high density memories with small feature size, the plasma etch process should be developed by well understanding and optimizing plasma behaviors. Therefore, it is necessary that the etch behavior of $HfO_2$ and plasma parameters are systematically investigated as functions of process parameters including gas mixing ratio, rf power, pressure and temperature to determine the mechanism of plasma induced damage. However, there is few studies on the the etch mechanism and the surface reactions in $BCl_3$ based plasma to etch $HfO_2$ thin films. In this work, the samples of $HfO_2$ were prepared on Si wafer with using atomic layer deposition. In our previous work, the maximum etch rate of $BCl_3$/Ar were obtained 20% $BCl_3$/ 80% Ar. Over 20% $BCl_3$ addition, the etch rate of $HfO_2$ decreased. The etching rate of $HfO_2$ and selectivity of $HfO_2$ to Si were investigated with using in inductively coupled plasma etching system (ICP) and $BCl_3/Cl_2$/Ar plasma. The change of volume densities of radical and atoms were monitored with using optical emission spectroscopy analysis (OES). The variations of components of etched surfaces for $HfO_2$ was investigated with using x-ray photo electron spectroscopy (XPS). In order to investigate the accumulation of etch by products during etch process, the exposed surface of $HfO_2$ in $BCl_3/Cl_2$/Ar plasma was compared with surface of as-doped $HfO_2$ and all the surfaces of samples were examined with field emission scanning electron microscopy and atomic force microscope (AFM).

• Journal of the Korean Vacuum Society
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• v.22 no.4
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• pp.188-192
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• 2013

Many studies have been conducted for preventing from diffusion between silicon wafer and metallic thin film due to a decrease of line-width and multi-layer thin film for miniaturization and high integration of semiconductor. This paper has focused on the nano-mechanical property of diffusion barrier which sample is prepared for various gas flow rate of nitrogen with tungsten (W) base from 2.5 to 10 sccm. The deposition rate, resistivity and crystallographic properties were measured by a ${\beta}$-ray back-scattering spectroscopy, 4-point probe and x-ray diffraction (XRD), respectively. We also has investigated the nano-mechanical property using the nano-indenter. As a result, the surface hardness of W-N thin film was increased rapidly from 10.07 to 15.55 GPa when the nitrogen gas flow was increased from 2.5 to 5 sccm. And the surface hardness of W-N thin film had 12.65 and 12.77 GPa at the nitrogen gas flow of 7.5 and 10 sccm respectively. These results were decreased by the comparison with the W-N thin film at nitrogen gas flow of 5 sccm. It was inferred that these severe changes were caused by the stoichiometric difference between the crystalline and amorphous state in W-N thin film. In addition, these results were caused by increased compressive stress.

• Journal of Internet of Things and Convergence
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• v.6 no.4
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• pp.21-26
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• 2020

An autonomous driving system is based on the deep learning system built by big data which are obtained by various IoT sensors. The miniaturization and high performance of the IoT sensors are needed for diverse devices including the autonomous driving system. Specially, the miniaturization of the sensors leads to compel the miniaturization of the fixer structures. In the viewpoint of the miniaturization, metallic structure is a best solution to attach the small IoT sensors to the main body. However, it is hard to manufacture the small metallic structure with a conventional machining process or manufacturing cost greatly increases. As one of solutions for the problems, in this work, metallic FDM (Fused depositon modeling) based on metallic filament was proposed and the FDM process was investigated to fabricate the small metallic structure. Final part was obtained by the post-process that consists of debinding and sintering. In this work, the relationship between infill rate and the density of the part after the post-process was investigated. The investigation of the relationship is based on the fact that the infill rate and the density obtained from the post-processing is not same. It can be said that this work is a fundamental research to obtain the higher density of the printed part.

• Korean Journal of Poultry Science
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• v.29 no.1
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• pp.37-43
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• 2002

This experiment was conducted to study the effect of early-life feed restriction with diet dilution on compensatory growth, feed efficiency and abdominal fat pad deposition in broilers. In this study, the chicks were randomly assigned to five treatments. Twenty chicks were assigned to each floor pen, and each dietary treatment was replicated with three pens. Birds In control group (C) were full-fed a starter diet throughout the experimental period, and all birds in four dietary treatments (T1-T4) were fed as starter diet diluted with 50% rice hulls. Birds in T1 were fed with a diluted starter diet ad libitum from 7- to 74-d. In T2,the feeding program was 1-d withdrawal alternating with 3-d feed and in T3 1-d withdrawal alternating with 2-d feed. The feeding Program in T4 was alternate days withdrawal and feeding. The feeding with the diluted starter diet (T1) did not significantly affect to growth rate as compared to the birds of C. When periods of 24 h feed withdrawal were Imposed in conjunction with the diluted diets, birds were under weight at 49 d. As the diluted diet treatment was combined with feed withdrawal (T2-T4), there were further less growth. During the 22 to 49 d Period,T1 birds had greater weight gain compared to other treatments (P<0.05) . Birds consumed less feed from 7- to 49-d when the rice hull dilution was used, and this effect was increased by imposition of feed withdrawal (P<0.07) . If rice hull was excluded from the calculation of feed intake (assumed indigestible) then Intake of the starter diet was markedly less for restricted vs. control birds. After 22 d and from 7 to 49 d, restricted birds had superior feed conversion (P<0.05) compared to control birds. Abdominal fat pad deposition and mortality were not influenced by early feed restriction by diluted diet (P<0.05) .

• Applied Chemistry for Engineering
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• v.24 no.5
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• pp.551-557
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• 2013

In the present study, pristine carbon nanotube (p-CNT) and thiolated carbon naotube (t-CNT) electrodes were investigated to improve their detectabilities for cadmium (Cd) and lead (Pb). In addition, we evaluate which reaction mechanism is used when the electrolyte contains both Cd and Pb metals. Square wave stripping was employed for analyzing the sensitivity for the metals. A frequency of 30 Hz, a deposition potential of -1.2 V vs. Ag/AgCl and a deposition time of 300 s were used as optimal SWSV parameters. t-CNT electrodes show the better sensitivity for both Cd and Pb metals than that of p-CNT electrodes. In case of Cd, sensitivities of p-CNT and t-CNT electrodes were $3.1{\mu}A/{\mu}M$ and $4.6{\mu}A/{\mu}M$, respectively, while the sensitivities for Pb were $6.5{\mu}A/{\mu}M$ (p-CNT) and $9.9{\mu}A/{\mu}M$ (t-CNT), respectively. The better sensitivity of p-CNT electrodes is due to the enhancement in the reaction rate of metal ions that are facilitated by thiol groups attached on the surface of CNT. When sensitivity was measured for the detection of Cd and Pb metals present simultaneously in the electrolyte, Pb indicates better sensitivity than Cd irrespective of electrode types. It is ascribed to the low standard electrode potential of Pb, which then promotes the possibility of oxidation reaction of the Pb metal ions. In turn, the Pb metal ions are deposited on the electrode surface faster than that of Cd metal ions and cover the electrode surface during deposition step, and thus Pb metals that cover the large portion of the surface are more easily stripped than that of Cd metals during stripping step.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2000.11a
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• pp.3-4
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• 2000

Many researchers are interested in the synthesis and characterization of carbon nitride and diamond-like carbon (DLq because they show excellent mechanical properties such as low friction and high wear resistance and excellent electrical properties such as controllable electical resistivity and good field electron emission. We have deposited amorphous carbon nitride (a-C:N) thin films and DLC thin films by shielded arc ion plating (SAIP) and evaluated the structural and tribological properties. The application of appropriate negative bias on substrates is effective to increase the film hardness and wear resistance. This paper reports on the deposition and tribological OLC films in relation to the substrate bias voltage (Vs). films are compared with those of the OLC films. A high purity sintered graphite target was mounted on a cathode as a carbon source. Nitrogen or argon was introduced into a deposition chamber through each mass flow controller. After the initiation of an arc plasma at 60 A and 1 Pa, the target surface was heated and evaporated by the plasma. Carbon atoms and clusters evaporated from the target were ionized partially and reacted with activated nitrogen species, and a carbon nitride film was deposited onto a Si (100) substrate when we used nitrogen as a reactant gas. The surface of the growing film also reacted with activated nitrogen species. Carbon macropartic1es (0.1 -100 maicro-m) evaporated from the target at the same time were not ionized and did not react fully with nitrogen species. These macroparticles interfered with the formation of the carbon nitride film. Therefore we set a shielding plate made of stainless steel between the target and the substrate to trap the macropartic1es. This shielding method is very effective to prepare smooth a-CN films. We, therefore, call this method "shielded arc ion plating (SAIP)". For the deposition of DLC films we used argon instead of nitrogen. Films of about 150 nm in thickness were deposited onto Si substrates. Their structures, chemical compositions and chemical bonding states were analyzed by using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and infrared spectroscopy. Hardness of the films was measured with a nanointender interfaced with an atomic force microscope (AFM). A Berkovich-type diamond tip whose radius was less than 100 nm was used for the measurement. A force-displacement curve of each film was measured at a peak load force of 250 maicro-N. Load, hold and unload times for each indentation were 2.5, 0 and 2.5 s, respectively. Hardness of each film was determined from five force-displacement curves. Wear resistance of the films was analyzed as follows. First, each film surface was scanned with the diamond tip at a constant load force of 20 maicro-N. The tip scanning was repeated 30 times in a 1 urn-square region with 512 lines at a scanning rate of 2 um/ s. After this tip-scanning, the film surface was observed in the AFM mode at a constant force of 5 maicro-N with the same Berkovich-type tip. The hardness of a-CN films was less dependent on Vs. The hardness of the film deposited at Vs=O V in a nitrogen plasma was about 10 GPa and almost similar to that of Si. It slightly increased to 12 - 15 GPa when a bias voltage of -100 - -500 V was applied to the substrate with showing its maximum at Vs=-300 V. The film deposited at Vs=O V was least wear resistant which was consistent with its lowest hardness. The biased films became more wear resistant. Particularly the film deposited at Vs=-300 V showed remarkable wear resistance. Its wear depth was too shallow to be measured with AFM. On the other hand, the DLC film, deposited at Vs=-l00 V in an argon plasma, whose hardness was 35 GPa was obviously worn under the same wear test conditions. The a-C:N films show higher wear resistance than DLC films and are useful for wear resistant coatings on various mechanical and electronic parts.nic parts.

• Journal of Practical Agriculture & Fisheries Research
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• v.6 no.1
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• pp.116-135
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• 2004

This study was conducted to investigate effects of spent composts of Se-enriched mushrooms as the dietary Se source on muscular Se deposition and plasma glutathione peroxidase (GSH-Px) activity in the finishing Hanwoo steer. Twenty Hanwoo steers were used in the experiment and they were divided into four groups in a randomized complete block design with five replicates. Treatments were four levels (0.1, 0.3, 0.6 and 0.9ppm as fed basis) of dietary Se from the combination with spent composts of Se-enriched mushrooms and/or Se non-enriched mushrooms, in which each treatment was formulated with corn and corn gluten meal and so forth. Treatment diets were fed to Hanwoo steers for 90 days until the slaughter. Dry matter intakes had no significant differences among treatments and there were no significant differences for performances such as total BW gain and ADG among treatments. The Se concentration in blood was linearly increased with increasing dietary selenium levels and reached a plateau level after 8 weeks (p<0.001). Plasma GSH-Px activities had the similar trends to blood Se concentrations by showing that the increased dietary Se level significantly increased plasma GSH-Px activities of both total and Se-dependent (p<0.001). Muscle Se contents of Se-supplemented groups were linearly increased by 1.35 ~ 1.68 folds compared with the control group (0.1ppm; 0.273㎍/dry g) and especially those of the hind legs for 0.9ppm treatment showed the highest Se content as shown 0.457㎍ per dry gram (p<0.01) corresponding to approximately 70% increase of the control group. Se retention rate in the muscle of dietary Se originated from spent composts of Se-enriched mushrooms was estimated of maximum approximately 30% and dietary Se content showed the significant correlation with plasma GSH-Px activities and muscle Se contents (p<0.01). Accordingly, Se present in spent composts of Se-enriched mushroom as the dietary Se source not only had great bioavailabilities showing higher blood Se concentration and plasma GSH-Px activities, but also increased Se deposition in the muscle for Hanwoo beef cattle.

• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.441-447
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• 2023

Lead(Pb), which is currently mainly used for shielding purposes in the medical radiation, has excellent radiation shielding functions, but is continuously exposed to radiation directly or indirectly due to the harmfulness of lead itself to the human body and the inconvenience caused by its heavy weight. Research on shielding materials that are human-friendly, lightweight, and convenient to use that can block risks and replace lead is continuously being conducted. In this study, based on the commonly used polyethylene terephthalate (PET) film and the fabric material used in actual radiation protective clothing, a multi-layer thin film was realized through sputtering and vacuum deposition of bismuth, tungsten, and tin, which are metal materials that can shield radiation. Thus, a shielding film was produced and its applicability as a radiation shielding material was evaluated. The radiation shielding film was manufactured by establishing the optimized conditions for each shielding material while controlling the applied voltage, roll driving speed, and gas supply amount to manufacture the shielding film. The adhesion between the parent material and the shielding metal thin film was confirmed by Cross-cut 100/100, and the stability of the thin film was confirmed through a hot water test for 1 hour to measure the change of the thin film over time. The shielding performance of the finally realized shielding film was measured by the Korea association for radiation application (KARA), and the test conditions (inverse wide beam, tube voltage 50 kV, half layer 1.828 mmAl) were set to obtain an attenuation ratio of 16.4 (initial value 0.300 mGy/s, measured value 0.018 mGy/s) and damping ratio 4.31 (initial value 0.300 mGy/s, measured value 0.069 mGy/s) were obtained. by securing process efficiency for future commercialization, light and shielding films and fabrics were used to lay the foundation for the application of films to radiation protective clothing or construction materials with shielding functions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.738-739
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• 2008

The SiOC film of carbon centered system was prepared using bistrimethylsilymethane and oxygen mixed precursor by the chemical vapor deposition. The chemical properties of he SiOC film were analyzed by the contact angle and FTIR spectra. The dielectric constant of the deposited films decreased after annealing process, and the correlation between the increasing the BTMSM/O2 flow rate ratio and he dielectric constant did not exist. However, the trend of increasing or decreasing of the dielectric constant repeated and here is the correlation ship between the dielectric constant and the Si-O-C bond in the range of $950{\sim}1200\;cm^{-1}$. The dielectric constant decreased between samples with the chemical shift. The lowest dielectric constant was 1.65 at the sample, which was observed he chemical shift.

• Journal of Surface Science and Engineering
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• v.41 no.5
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• pp.240-244
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• 2008

Composite plating is a method of co-deposition of plating layer with metallic and/or non-metallic particles to improve the plating layer properties such as high corrosion resistance and photolysis of organic compounds. The properties of nickel-ceramic composite plating are significantly depend on the surface characteristics of co-deposited particles as well as the quantity in electrolyte. In this study, Ni-$TiO_2$ composite coating layer was produced by electrodeposition technique from non-aqueous eletrolyte and its surface characteristics as well as photolytic properties were investigated. The amounts of immobilized $TiO_2$ particles increased with increasing the initial $TiO_2$ particles contents in the bath. Samples electroplated with the current density of $0.5\;A/dm^2$ showed the significantly improved homogeneous $TiO_2$ particles distribution. The corrosion resistance of Ni-$TiO_2$ composite coating layer also improved with increaing the amounts of $TiO_2$ particles. Etched sample showed about 10% increased photolytic rate of organic matter compare to that of the non-etched.